(1) Field of the Invention
The invention relates to underwater vehicle communications and is directed more particularly to a new form of floating wire also known as a buoyant cable antenna element suitable for underwater vehicle communications.
(2) Description of the Prior Art
A buoyant cable antenna consists of a straight insulated wire that is positively buoyant and designed to float to the ocean surface when released by a submerged underwater vessel. The wire may be either a solid or stranded copper conductor of uniform diameter along its length. It is often connected to the underwater vehicle by means of a standard coaxial transmission line at one end. The other end of the wire is terminated either in a shorting cap (to connect it to the ocean) or an insulating cap (to isolate it from the ocean.) The choice of cap is determined by the mode of operation that the operator wishes. The buoyant cable antenna is one of a host of submarine antennas currently in use that allow a submarine to perform electromagnetic communications while it is submerged.
Prior art antennas suffer from limited performance in the commercial high frequency (HF) band of 2 to 30 MHZ. This limited performance is due to the limited band width of the prior art antenna elements. It has become apparent that there is a need for a buoyant cable antenna element that can improve the bandwidth of the antenna in the HF band.